US Bridges

SB I-380 over 33rd Ave

Fair

Linn County, Iowa · 1.3 Mi. N of Jct. U.S. 30 · Structure no. 000000000603022

Built
1974
51 years old
Condition
Fair
inspected January 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
171 ft
3 main spans
Daily traffic
28,600
2022 count
Owner
State
State Highway Agency

About this bridge

SB I-380 over 33rd Ave is a prestressed concrete stringer/multi-beam or girder carrying SB I-380 over 33rd Ave in Linn County, Iowa. It was built in 1974, so it is 51 years old, older than the Iowa average of 45.5 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 28,600 vehicles a day, roughly 12% of them trucks, projected to reach 28,600 by 2043. The structure is 171 ft (52.1 m) long and 55 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesSB I-380
Crosses33rd Ave
Location1.3 Mi. N of Jct. U.S. 30
RouteInterstate 380
CountyLinn County
StateIowa
Coordinates41.94529, -91.67074
Functional classUrban Principal Arterial - Interstate

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Last inspectionJanuary 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating86.5 US tons
Inventory rating32.5 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length171 ft (52.1 m)
Longest span87 ft (26.5 m)
Deck width55 ft (16.9 m)
Roadway width52 ft (15.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic28,600 (2022)
Projected traffic28,600 by 2043
Trucks12%
Lanes on structure3
Traffic directionOne-way traffic
CarriesOverpass structure at an interchange
CrossesHighway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was SB I-380 over 33rd Ave built?

It was built in 1974, making it 51 years old in 2025.

What condition is SB I-380 over 33rd Ave in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in January 2023.

How much traffic does SB I-380 over 33rd Ave carry?

About 28,600 vehicles per day (2022 count), of which roughly 12% are trucks.

How long is SB I-380 over 33rd Ave?

The structure is 171 ft (52.1 m) long with a longest span of 87 ft (26.5 m) and a deck 55 ft wide.

Who owns SB I-380 over 33rd Ave?

It is owned by the State Highway Agency.